fluent nhibernate cascade for graph

Question

To understand cascade better. Can someone please explain why in the situation below node C and D are not persisted? Thanks.

public class Node : Entity
{
    public virtual Node Previous { get; set; }
    public virtual Node Next { get; set; }
    public virtual string Name { get; set; }

    public Node() { }
    public Node(string Name)
    {
        this.Name = Name;
    }

    public virtual void Connect(Node Previous, Node Next)
    {
        this.Previous = Previous;
        this.Next = Next;
    }
}

Mapping:

public class NodeMap : IAutoMappingOverride<Node>
{
    public void Override(AutoMapping<Node> mapping)
    {
        mapping.References(x => x.Previous).Cascade.SaveUpdate(); 
        mapping.References(x => x.Next).Cascade.SaveUpdate(); 
    }
}

Data creation:

INHibernateRepository<Node> NodeRepository = new NHibernateRepository<Node>();

Node A = new Node("A");
Node B = new Node("A");
Node C = new Node("C");
Node D = new Node("D");
Node E = new Node("E");
Node F = new Node("F");

A.Connect(null, B);
B.Connect(A, E);
C.Connect(B, E);
D.Connect(B, E);
E.Connect(B, F);
F.Connect(E, null);

NodeRepository.SaveOrUpdate(A);
NodeRepository.DbContext.CommitChanges();

I could not find which node you are placing to the repository — hazzik, Aug 01 '12 at 12:22

score 2 · Accepted Answer · answered Aug 01 '12 at 12:57

2

Your grapth looks like following

A <-> B <-> E <-> F

B <- C -> E
B <- D -> E

As you can see you have no links from A to C and from A to D (only in the opposite direction)

So, when you save A NHibernate is tring to save all dependencies of A, and finds unsaved B, then E and then F.

answered Aug 01 '12 at 12:57

hazzik

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I thought so. Is there anything I can do to achieve what I want, which only requires me to save the top node (A)? – cs0815 Aug 01 '12 at 13:20
Unfortunately no. You need `C` and `D` to be reachable from `A` – hazzik Aug 01 '12 at 13:24

fluent nhibernate cascade for graph

1 Answers1